NB Sizes quoted are side lengths of pentaliths to convert to lith diameter multiply by 1.5 to convert to coccosphere diameter mutliply by 3. Genotypes I & II and IV & V formed clusters supporting the morphological separation. The degree of separation between the genotype groups suggested that the morphotypes were well-diverged species. No consistent differences between the forms were seen apart from size.

Short diagnosis: Pentaliths pentagonal with sraight edges and flat top surface

Morphology remarks: Coccosphere are regular pentagonal dodecahedra with the plates closely butting to form a continuous cover. Liths pentagonal, surface smooth, flat or gently concave. Sutures show clockwise obliquity in distal view, running from centre to approx 3/8 of the way along side of the pentalith. Pentalith diameter varies from about 1.5 to 7µm but in single samples all pentaliths are usually of very similar size. It is likely that several pseudo-cryptic species occur within the modern B. bigelowii (Takano et al. 2006, Hagino 2009).Ecology & Biogeography: Neritic - predominanty observed in shelf seas, oceanic occurrences much rarer.Biology & life-cycles: Never cultured, depite numerous attempts (J. Green, C. Klass, I. Probert, K. Hagino pers. coms.).

Gran, H.H. & Braarud, T., (1935). A quantitative study of the phytoplankton in the Bay of Fundy and the Gulf of Maine (including observations on hydrography, chemistry and turbidity). Journal of the Biological Board of Canada, 1: 279-467.